1. Field of the Invention
The present invention relates to capacity reservation in the field of output planning processes, and particularly to a system and method of reserving capacity for a pre-process order for a semiconductor product family produced in a semiconductor foundry.
2. Description of the Related Art
In recent years, many enterprises or manufacturers have introduced the concept of supply chain management to integrate their internal and external resources. The supply chain entails functions of purchase of materials, transformation of these materials into intermediate and finished products, and the distribution of these finished products to customers. In the supply chain, customers transmit requests or demands can include of a request for a particular quantity of a product by a specific date to a manufacturer, and the manufacturer plans its manufacturing schedule according to these received requests to satisfy each customer.
In a manufacturing plant, such as a semiconductor foundry in which a plurality of semiconductor products is produced, it is desirable to schedule manufacturing operations based upon the quantities of the products ordered from the customer requests. Failure to properly schedule manufacturing operations may result in late manufacture of the product and/or missed customer deadlines. Accordingly, when an order from a customer is taken, it is important for manufacturing systems to deliver requested products on time. Thus, meeting delivery dates is crucial in assuring that ordered products can be provided in a timely manner.
Many conventional scheduling systems have been developed to manage the above-mentioned manufacturing scheduling. For example, U.S. Pat. No. 5,093,794 entitled “Job Scheduling System” discloses a job scheduling system, providing scheduling of a variety of jobs without special purpose coding by the use of time maps to maintain current data, as well as scheduling jobs around potential bottlenecks of shop resources in a dynamic manner.
Further, U.S. Pat. No. 6,415,260 entitled “Dynamic Capacity Demand Forecast System” discloses a capacity-demand-forecast system for the manufacture of semiconductor integrated circuits. According to the capacity-demand-forecast system, when a number of products and a plurality of processing steps are provided in a processing line, the turn ratio of each product at each stage on a specified working day is calculated and the work-in-process (WIP) or the lots of every product at each stage on the same day is determined. According to these two numbers, the WIP on the next working day can be calculated, and the next working day's flow is determined. In this way, the flow of each product at each future stage is determined, and the cumulative flow of all products at all stages in a working day is equal to the capacity demand on the processing line for that day. Throughput of wafers may thus be determined, allowing adjustment of the parameters of the processing line.
Typically, a manufacturing plant produces more than one type of product. The manufacturing processes of these products may partially comprise common technology requirements and manufacturing conditions. In this case, products sharing elements of the manufacturing process can be categorized as a “product family,” a consideration not particularly emphasized in the cited patents.
FIG. 1 shows an example of a product family produced in a semiconductor foundry, in which the product family includes six types of IC chips A, B, C, D, E and F. Generally, the semiconductor foundry may have a plurality of lots. A preprocess 310 produces a component of all the six types of IC chips A to F. The fabricated components are then stored in “stock” 330, for subsequent processing. When a demand for a particular type of IC chip, e.g. IC chip C, occurs, a post-process operation 323 corresponding to IC chip C is performed on the components stored in the stock 330 to obtain the requested IC chips C. Similarly, each of the post-processing operations 321–326 corresponding to the IC chips A to F can be performed according to the demand for the product family.
In this case, generally, there are two types of orders from customers with demand for the IC chips. For example, when a customer decides that a demand for a particular type of IC chip in the product family may be required in the coming season, the customer may submit a “pre-process order,” or a so-called “bank order,” for the components of the product family stored in the stock 330 as shown in FIG. 1. When the components of the product family are produced and stored in the stock, the customer may further submit a follow-up order corresponding to the particular type of IC chip, e.g. IC chip C. This follow-up order is a post-process order. Products such as the IC chip, in the product family are usually categorized with a series of codes. Thus, a management model according to pre-process orders and the post-process orders of the product family can be obtained.
In production element preparation, a material requirement planning (MRP) system is generally introduced. In a manufacturing foundry fabricating the above-mentioned product family, a bill of material (BOM) for the pre-process order, which corresponds to the component, and a group of BOMs for the post-process orders, which corresponds to the products in the product family, are provided to the MRP system. Thus, when a pre-process order or a post-process order is received, material for the components is prepared according to the BOM for the pre-process order or the post-process order.
However, since the complexity of the supply chain varies greatly from industry to industry and firm to firm, production element preparation may vary. For example, in a semiconductor foundry, capacity management is significant for reducing inventory and increasing productivity. Since the manufacturing process of each semiconductor product is complicated, capacity preparation, rather than material preparation, is emphasized. Thus, the system focusing on MRP and BOMs for pre-process orders or post-process orders must be modified.
According to a system using a modified MRP system and BOM, a pre-process operation BOM, related to pre-process capacity, and a plurality of post-process operation BOMs related to post-process operating capacity are provided. When a pre-process order is received before a cutoff date, the pre-process capacity is reserved, and when a post-process order is received before the cutoff date, the post-process operating capacity is reserved.
In the manufacturing plant, e.g. the semiconductor foundry, the pre-process order is generally provided with capacity “available to promise” (ATP) support, since the components produced and stored in the stock can be interchanged. However, it is harder to predict post-process orders from the customer. Even if a post-process order is received before the cutoff date, it is possible that most of the capacity may be reserved when the manufacturing plant, e.g. the semiconductor foundry, is in full-load status. In this case, only remnant supplies are available for the post-process order, as a result of failure to properly schedule manufacturing operations.